Mark-forming record materials

ABSTRACT

A chromogenic material of normally colorless form is disclosed, having a structural formula:   R2 represents hydrogen and alkyl radicals; and R3 represents hydrogen and alkyl radicals having less than five carbon atoms; said materials assuming a colored from upon reactive contact with a Lewis acid molecule. Examples include 6&#39;&#39;-diethylamino-2&#39;&#39;formylfluoran; 2&#39;&#39;-carbomethyoxy-6&#39;&#39;-diethylaminofluoran; and 2&#39;&#39;benzoyl-6&#39;&#39;-diethylamino-4&#39;&#39;-methylfluoran.

United States Patent [191 Lin [ Feb. 6, 1973 I 1 MARK-FORMING RECORDMATERIALS [75] Inventor: Chao-Han Lin, Dayton, Ohio [73] Assignee: TheNational Cash Register Com pany, Dayton, Ohio [22] Filed: March 1, 1971[21] Appl. No.: 119,830

Related US. Application Data [62] Division of Ser. No. 792,325, Jan. 21,1969, Pat. No.

[52] US. Cl. ..1l7/36.2,1l7/36.8,117/155 L [51] Int. Cl. ..B4lm 5/22[58] Field of Search ..1 17/362 [56] References Cited UNITED STATESPATENTS 3,514,310 5/1970 Kimura et a1 ..117/36.2 3,455,721 7/1969Phillps ct a1. ..1 17/362 3,539,375 1 1/1970 Baum 117/368 PrimaryExaminer-Murray Katz Att0rneyE. Frank McKinney et a1.

[57] ABSTRACT A chromogenic material of normally colorless form isdisclosed, having a structural formula:

wherein R represents -CO-R,, and wherein R represents hydrogen, -OCH andR represents hydrogen and alkyl radicals; and R represents hydrogen andalkyl radicals having less than five carbon atoms; said materialsassuming a colored from upon reactive contact with a Lewis acidmolecule. Examples include 6-diethylamino- 2-for-mylfluoran:2-carbomethyoxy-6-diethylaminofluoran; and 2-benzoyl-6-diethylamino-4-methylfluoran.

19 Claims, 2 Drawing Figures COATED ON THE REAR WITH MINUTE PRESSURE-RUPTURABLE CAPSULES CONTAINING LIQUID SOLUTION OF CHROMOGENIC MATERIALDEVELOPABLE ON CONTACT WITH AN ELECTRON- ACCEPTING MATERIAL OF THELEWIS- ACID TYPE TO COLORED FORM RECEIVING SURFACE OF UNDERSHEET COATEDWITH AN ELECTRON-ACCEPTING MATERIAL OF THE LEWIS- ACID TYPE PATENIEDFEB6 I975 3.715.226

BASE- SHEET OF RECORD MATERIAL COATEDON THE REAR WITH MINUTEPRESSURE-RUPTURABLE CAPSULES CONTAINING LIQUID SOLUTION OF CHROMOGENICMATERIAL DEVELOPABLE ON CONTACT WITH AN ELECTRON-' ACCEPTING MATERIAL OFTHE LEWIS- ACID TYPE TO COLORED FORM RECEIVING SURFACE OF UNDERSHEETCOATED WITH AN ELECTRON-ACCEPTING MATERIAL OF THE LEWIS- ACID TYPEQW/XZJ/AZ/X MARK-FORMING RECORD MATERIALS This is a division ofapplication Ser. No. 792,325, filed Jan. 21, 1969 now U.S. Pat. No.3,697,757.

BACKGROUND OF THE INVENTION This invention pertains to chromogeniccompounds for use in pressure sensitive record material and to animproved mark-forming manifold system incorporating these chromogeniccompounds. More specifically, this invention pertains to acyl-, ether-,and ester-substituted dialkylamino fluorans which have the form ofsubstantially colorless, i.e., white, or slightly colored solids, orapproach being colorless when in liquid solution, but which may beconverted to dark-colored forms upon reactive contact with appropriateacidic material. As used in mark-forming systems, marking in desiredareas on support webs or sheets may be accomplished by effectinglocalized reactive contact between the chromogenic material and theacidic material on or in such a web or sheet, such material beingbrought thereto by transfer, or originally there, in situ, the desiredreactive contact forming dark-colored materials in the intended imageareas.

Pressure-sensitive, mark-forming systems of the prior art include thatdisclosed in Application for Letters U.S. Pat. No. 392,404 (nowabandoned) filed Aug. 27, 1964, in the names of Robert E. Miller andPaul S. Phillips, Jr. The above-mentioned patent application provides amarking system of disposing on and/or within sheet support material,mutually reactant but unreacted mark-forming components (at least onecomponent of which is a polymeric material) and a liquid solvent inwhich each of the mark-forming components is soluble, said liquidsolvent being present in such form that it is maintained isolated by apressure-rupturable barrier from at least one of the markformingcomponents until an application of pressure causes a breach or ruptureof the barrier in the area delineated by the pressure pattern. Themark-forming components thereby are brought into reactive contact,producing a distinctive mark.

It is an object of this invention to provide new and improved substanceshaving chromogenic properties which may be incorporated in a web orcoated onto the surface of a web to provide a manifolding unit, andwhich are, moreover, useful in carrying out improved methods of markinginvolving reactive contact with a color-activating material to yielddarkcolored reaction products in areas where marking is desired.

It is another object of this invention to provide compounds, based uponthe acyl-, ether-, and ester-substituted dialkylamino fluorans disclosedherein which are substantially colorless, or slightly colored offering anew and improved variety of chromogenic characteristics, and yieldingnovel dark-colored substances upon contact with color-activatingmaterials.

It is a further object of this invention to provide new and improved,normally substantially colorless,

chromogenic substances yielding Lewis acid-reacted color products whichexhibit improved color stability on exposure to light and improvedreproduction capabilities when copied by xerographic ordiazo processes.

lt is a further object of this invention to provide new and improved,normally substantially colorless, chromogenic substances yieldingcolored reaction products when placed in reactive contact with certainselected Lewis acid materials.

It is a further object of this invention to provide a new and improvedmark-forming system which comprises disposing, within a web or upon thesurface of a web or sheet-support-material, unreacted chromogenicmaterial in a location suitable for subsequent reactive contact with anacidic material to produce darkcolored reaction products, thus providingmeans for making marks of desirable color intensity and hue.

In accordance with one feature of this invention, there is provided a,substantially colorless or slightly colored, chromogenic compound havingthe structural formula:

ll: It g 1 wherein R represents -CO-R and wherein R represents hydrogen-O-CH and,

R represents hydrogen and alkyl radicals having less than five carbonatoms; and R represents hydrogen radicals and alkyl radicals having lessthen five carbon atoms. Examples of these novel compound include 6'-diethylamino-2-formylfluoran having the structural formula: (MILK /N -o\C2115 l 0 I CH=O 2'-carbomethoxy-6-diethylaminofluoran having thestructural formula:

Cam I O :-0-cH= I 020 0 2'-benzoyl-6'-diethylamino-4-methylfluoranhaving the structural formula:

H (:m our, \N -U 12115 In accordance with another feature of thisinvention, a new composition of matter is disclosed which comprises adark-colored product of chemical reaction having a resonant chemicalstructure and produced by contact of a color-activating material withone of the above-mentioned chromogenic compounds. The colordeveloping oractivating material is an acidic substance useful for converting thechromogenic compounds to colored forms.

The method of marking of this invention, i.e., the method of developinga dark-colored material from substantially colorless or slightly coloredchromogenic compounds, comprises providing a chromogenic compoundselected from among the above-mentioned compounds and bringing suchchromogenic compound into reactive contact with an acidiccolor-activating substance, in areas where marking is desired, toproduce a dark-colored form of the chromogenic compound by the actionthereon of said acidic substance.

Acidic materials employed in this invention can be any compound withinthe definition of a Lewis acid, i.e., any electron acceptor. Preferably,acidic organic polymers such as phenolic polymers are employed as theacidic material. The novel chromogenic materials exhibit the advantageof improved color stability when they are reacted with such phenolicpolymers. Solution formation of solid particles of the polymericmaterial in a solvent system with the substantially colorlesschromogenic compounds permits penetration of the dark-colored reactionproduct into a porous support sheet, e.g., paper, so that the coloredform of the chromogenic material is absorbed into the body of the sheetand is not merely on the surface of the sheet. The absorption featureprovides protection against erasure of recorded data by attrition of thesurface of a record sheet made in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic representationof a twosheet unit manifold, in perspective. The bottom surface of theoverlying sheet is supplied on the surface or near the surface with amultiplicity of minute pressure-rupturable microcapsules containing asolution of the novel, substantially colorless, chromogenic component.An acidic component, such as an acid clay or a phenolic polymericmaterial lies within the lower web or undersheet or upon the uppersurface of the lower web or undersheet. A colored mark is made by theuse of a stylus, a type character, or other pressure-exerting meansapplied to the two-sheet unit manifold.

The encapsulated solution is released on the event of rupture of thecapsules in writing operations, as is shown in FIG. 2.

FIG. 2 is a sectioned view of the two-sheet unit manifold of FIG. 1. Theelements are not to scale and are so-shown in order to more effectivelydepict their interrelation. The released solution is transferred fromthe overlying or base-sheet to the receiving surface of the underlyingsheet in conformance with the pressure pattern of the writing operation.The drawing shows that the top of the underlying sheet is coated orimpregnated with a material reactant with the chromogenic material,e.g., an acid clay or an acidic phenolic polymer material; and thatcapsules are present on the overlying or base-sheet which capsulescontain a liquid solution of chromogenic material. In another embodimentof the record material, however, the capsules can contain the polymericphenolic material in liquid solution and the receiving surface of theunderlying sheet can be supplied with the chromogenic material. Theimprovement in the system resides in the chromogenic material, whichchromogenic material is the substance of the instant invention.

Referring again to FIG. 1, comprising an overlying or base-sheet havingthe chromogenic material located within or upon the sheet; it ispossible to incorporate the chromogenic material in a solid, crystallinestate in a binder material so that the chromogenic material may betransferred from the overlyingsheet, upon the application of pressure,to deposit some of the chromogenic material on the receiving surface ofthe undersheet, which receiving surface carries a color-activatingpolymeric material. Preferably, the chromogenic substance is dissolvedin an appropriate solvent and minute droplets of the solution of thechromogenic material are encapsulated in minute, rupturable, capsules.It is apparent that many other arrangements are possible, includingdifferent configurations and relationships of the solvent and all of themark-forming materials with respect to their encapsulation and locationon the supporting underlying or overlying sheets or webs can beenvisioned. Such arrangements are thoroughly described in theaforementioned application Ser. No. 392,404, (now abandoned) in thenames of Miller et al. and need not be repeated herein.

SUMMARY OF THE INVENTION It is noted that the polymeric mark-formingcomponents should have a common solubility with the novel chromogenicmaterial in at least one liquid solvent when the acid-reacting materialis a phenolic or other acidic organic polymer. It is also noted that ina single system several chromogenic materials may be used with the sameor different polymeric materials. Several polymeric materials can bereactively contacted with a single chromogenic compound or with amixture of chromogenic compounds.

As mentioned above, the solvent can be maintained in physical isolationin minute droplets until such time as it is released by application ofpressure. This may be accomplished by several known techniques, but,preferably, isolationis maintained by encapsulation of individualdroplets of the solvent in a microcapsule according to the proceduresdescribed, for example, in U.S. Pat. No. 2,712,507, issued July 5, 1955on the application of Barrett K. Green; U.S. Pat. No. 2,730,457 issuedJan. 10, 1956 on the application of Barrett K.

Green and Lowell Schleicher; U.S. Pat. No. 2,800,457,

issued July 23, 1957 on the application of Barrett K. Green and LowellSchleicher; U.S. Pat. No. 2,800,458, issued July 23, 1957 on theapplication of Barrett K. Green, reissued as U.S. Pat. No. RE. 24,899 onNov. 29, 1960; and U.S. Pat. No. 3,041,289 issued June 26, 1962 on theapplication of Bernard Katchen and Robert E. Miller. The microscopiccapsules, when disposed within or upon a supporting web as amultiplicity in contiguous juxtaposition, are rupturable by pressure,such as normal marking pressure found, for example, in writing or typingoperations.

The material or materials chosen as the wall material for thedroplet-containing microcapsules, in addition to being pressurerupturable, must be inert or unreactive with respect to the intendedcontents of the capsules and the other mark-forming components so thatthe capsule wall material will remain intact under normal storageconditions until such time as it is released by an application ofmarking pressure Preferred examples of eligible capsule wall materialsinclude gelatin, gum arabic and many others thoroughly described in theaforementioned patents.

For most uses in record material, the capsule size should not exceedabout 50 microns in diameter. Preferably, the capsules should be smallerthan about l5 microns in diameter.

The acidic organic polymeric material useful for developing the color ofnovel chromogenic compounds in this invention include phenolic polymers,phenol acetylene polymers, maleic acid-rosin resins, partially or whollyhydrolyzed styrene-maleic anhydride copolymers and ethylene-maleicanhydride copolymers, carboxy polymethylene and wholly or partiallyhydrolyzed vinylmethylether-maleic anhydride copolymer and mixturesthereof.

More specifically, phenolic polymers found useful include alkyl-phenolacetylene resins, which are soluble in common organic solvents andpossess permanent fusibility in the absence of being treated bycross-linking materials. Another specific group of useful phenolicpolymers are members of the type commonly referred to as novalaks, (atype of phenolformaldehyde polymeric material) which are characterizedby solubility in common organic solvents and which are, in the absenceof cross-linking agents, permanently fusible. Resol resins, if they arestill soluble, may be used, though they are subject to change inproperties upon aging. Generally, phenolic polymer material found usefulin practicing this invention is characterized by the presence ofhydroxyl groups and by the absence of groups'such as methylol, whichtend to promote infusibility or cross-linking of the polymer, andfurther, by being soluble in organic solvents and relatively insolublein aqueous media. Again, it should be remembered that mixtures of theseorganic polymers and other acidic materials can be employed.

A laboratory method useful in the selection of suitable phenolic resinsis the determination of the infrared absorption pattern. It has beenfound that phenolic resins which undergo absorption in the 3,2003,500cm" region (which is indicative of hydroxyl groups) on the resinmolecules and which do not absorb in the l,600-l,700 cm region areeligible. This latter absorption region is indicative of desensitizationof hydroxyl groups which desensitization renders such groups unavailablefor reaction with the chromogenic materials.

The preparation of some organic polymeric materials useful forpracticing this invention has been described in industrial andEngineering Chemistry, Volume 43, Pages 134 to 141, Jan. i951, and aparticular polymer thereof is described in Example I of US. Pat. No.2,052,093, issued to Herbert Honel on August 25, 1936. The preparationof the phenol-acetylene polymers has been described in Industrial andEngineering Chemistry," Volume 41, Pages 73 to 77, January, 1949. Thepreparation of maleic anhydride copolymers is described in theliterature, such as, for example, one of the maleic anhydride vinylcopolymers, as disclosed in Vinyl and Related Polymer," by Calvin E.Schildknecht, Second printing,

published April, 1959, by John Wiley & Sons, lncorporated: See pages 65to 68 (styrene-maleic anhydride copolymer), 530 to 531 (ethylene-maleicanhydride copolymer), and 628 to 630 (vinylmethylether-maleic anhydridecopolymer).

When the acidic material used as a mark-forming component in the presentinvention is one of the aforementioned organic polymers, the liquidsolvent chosen must be capable of dissolving it. The solvent may bevolatile or nonvolatile, and a singleor multiple-component solvent maybe used which is wholly or partially volatile. Examples of volatilesolvents useful in practicing the present invention include toluene,petroleum distillate, perchloroethylene, and xylene. Examples ofnonvolatile solvents include high-boiling-point petroleum fractions andchlorinated biphenyls. Generally, the solvent chosen should be capableof dissolving at least about 0.3 percent, by weight, of the chromogenicmaterial, and at least about 3 to 5 percent, by weight, of the acidicpolymeric material to yield an effective reaction. However, in thepreferred system, the solvent should be capable of dissolving an excessof the polymeric material, so as to provide every opportunity forutilization of the chromogenic material and, thus, to assure maximumcoloration at the reaction site.

A further criterion for selection of the solvent is that the solventmust not interfere with the mark-forming reaction. In some instances,the presence of the solvent may be found to interfere with themark-forming reaction or diminish the intensity of the mark, in whichinstances the solvent chosen should be sufficiently volatile to assureits removal from the reaction site soon after having brought themark-forming components into reactive contact so that the mark-formingreaction can proceed.

Since the mark-forming reaction requires that an intimate mixture of thecomponents be brought about through solution of said components, one ormore of the mark-forming components can be dissolved in solvent dropletsisolated by encapsulation, the only requirement being that at least oneof the components essential to the mark-forming reaction be maintainedisolated until the mark-forming reaction is desired.

in the usual case, the mark-forming components are so chosen as toproduce a mark upon application of pressure to a coated system of sheetsat room temperature (20 to 25 C.). However, the present invention alsoincludes a system wherein the solvent component is not liquid attemperatures near room temperature but is liquid and in condition forforming solutions only at elevated temperatures.

The support sheet member on which components of the system are disposedmay comprise a single or a dual sheet assembly. in the case where allcomponents are disposed on a single sheet, the record material isreferred to as a self-contained or autogenous system. Where there mustbe a migration of solvent, with or without the mark-forming component,from one sheet to another, the record material is referred to as atransfer system. (Such a system may also be referred to as a two-fold"system, in that at least two sheets are required and each sheet includesa component, or components, essential to the mark-forming reaction).Where an adequate amount of the colored reaction product is produced inliquid or dissolved form on a surface of one sheet, a colored mark canbe recorded on a second sheet by transfer of the colored reactionproduct.

In a preferred case, where microcapsules are employed, they can bepresent in the sheet support material either disposed therethroughout oras a coating thereon, or both. The capsules can be applied to the sheetmaterial as a dispersion in the liquid vehicle in which they weremanufactured, or, if desired, they can be separated from the vehicle andthereafter dispersed in a solution of the acid-reacting polymericcomponent (for instance, 30 grams of water and 53 grams of a l per cent,by weight, aqueous solution of polyvinylmethylether-maleic anhydride) toform a sheet-coating composition in which, because of the inertness ofthe solution and the capsules, both components retain their identity andphysical integrity. When this composition is disposed as a film on thesupport material and dried, the capsules are held therein subject torelease of the contained liquid by rupture of the capsule walls. Thelatter technique, relying on the inertness of the microcapsule and thedispersing medium of the filmforming mark-forming polymeric component,provides a method for preparing a sensitive record material coatinghaving the capsules interspersed directly in a dry film of the polymericmaterial as the film is laid down from solution. A further alternativeis to disperse one or more mark-forming components, and thechromogenic-material-containing microcapsules in a liquid medium not asolvent for either the mark-forming component or the microcapsules, withthe result that all components of the mark-forming system may bedisposed on or within the support sheet in the one operation. Of course,the several components may be applied individually. The capsules canalso be coated onto a sheet as a dispersion in a solution of polymericmaterial which is not necessarily reactive with the capsule-containedsolution of chromogenic materials.

The respective amounts of the several components can be varied accordingto the nature of the materials and the architecture of the recordmaterial unit desired or required. Suitable lower amounts include, inthe case of the chromogenic material, about 0.005 to 0.075 pound perream (a ream in this application meaning five hundred (500) sheets of 25X 38 inch paper, totalling 3,300 square feet); in the case of thesolvent, about 1 to 3 pounds per ream; and in the case of the polymer,about 0.5 pounds per ream. In all instances, the upper limit isprimarily a matter of economic consideration.

The slurry of capsules can be applied to a wet" web of paper, forexample, as it exists on the screen of a Fourdrinier paper machine, soas to penetrate the paper web a distance depending on the freeness ofthe pulp and the water content of the web at the point of application.The capsules can be placed directly in or on a paper or support sheet.Not only capsule structures, but continuous films which contain amultitude of microscopic, unencapsulated, droplets for local release inan area subjected to pressure can be utilized. (See, for example, U. S.Pat. No. 2,299,694 which issued Oct. 20, 1942, on the application ofBarrett K. Green.)

With respect to the acidic organic polymeric component, a solutionthereof in an evaporable solvent can be introduced into an amount ofwater and the resulting mixture can be agitated while the evaporablesolvent is blown off by an air blast. This operation leaves an aqueouscolloidal dispersion slurry of the polymeric material, which may beapplied to finished paper so as to leave a surface residue or the slurrymay be applied to a wet" web of paper of at the size-press station of apaper making machine. In another method for making a polymer-sensitizedsheet, the water-insoluble polymer can be ground to a desired orrequired particle size in a ball mill with water, preferably with adispersing agent, such as a small quantity of sodium silicate. If abinder material of hydrophilic properties is ground with the polymericmaterial, the binder itself may act as a dispersant. If desired, anamount of binder material of up to 40 per cent, by weight, of the amountof polymeric material can be added to the ball-milled slurry ofmaterials; -such binder materials being of the paper coating binderclass, including, for example, gum arabic, casein,hydroxyethyl-cellulose, and latexes (such as styrene-butadienecopolymer). If desired, oil absorbents in the form of fullers earths maybe combined with the polymeric material particles to assist inretaining, in situ, the liquid droplets of chromogenic material solutionto be transferred to it in datarepresenting configuration, for thepurpose of preventing bleeding of the print.

Another method for applying the chromogenic or polymeric materialindividually to a single sheet of paper is by immersing a sheet of paperin l-10 per cent, by weight, solution of the material in an evaporablesolvent. Of course, this operation must be conducted individually foreach reactant, because if the other reactant material were present,contact of the reactants would result in a premature coloration over thesheet area. A dried sheet with one component can then be coated with asolution of another component, the solvent of which is a non-solvent tothe already-supplied component.

The polymeric material can also be dissolved in ink composition vehiclesto form a printing ink of colorless character and, thus, may be used tospot-print a proposed record-sheet-unit sensitized for recording, in areaction-produced color in those spot-printed areas, by application of asolution of the chromogenic material. In the case of phenolic polymer, aprinting ink may be made of up to per cent, by weight, of the phenolicpolymeric material in a petroleum-based solvent; --the ink being builtto a viscosity suitable for printing purposes. The relative amounts ofreactive, mark-forming, components to be used in practice of thisinvention, are those most convenient and economical amounts consistentwith adequate, desired or required visibility of the recorded data. Theresolution of the recorded data is dependent on, among other things,particle or capsule size, distribution and amount of particles orcapsules, liquid solvent migration, chemical reaction efficiency, andother factors, all of which can be optimized empirically by one skilledin the art. Such factors do not determine the principle of the presentinvention, which invention, in part, relates to means for enabling thebringing into solution contact, by marking pressure, two normally solid,chemically reactive, components dissolved in a common liquid solventcomponent held isolated as liquid droplets. The isolated liquid dropletsare preferably in marking-pressure-rupturable capsules havingpolymericnfilm walls, or are isolated, as a discontinuous phase, in acontinuous marking-pressure-rupturable film.

In the color system of this invention the acidic markforming materialreacts with the chromogenic material to effect distinctive colorformation or color change. In a multi-sheet system in which an acidicorganic polymer is employed, it may be desirable to include othermaterials to supplement the polymer reactants. For example, kaolin canbe added to improve the transfer of the liquid and/or the dissolvedmaterials between the sheets. In addition, other materials such asbentonite, attapulgite, talc, feldspar, halloysite, magnesiumtrisilicate, silica gel, pyrophyllite, zinc sulfate, calcium sulfate,calcium citrate, calcium phosphate, calcium fluoride, barium sulfate andtannic acid can be included.

Various methods known to the prior art and others disclosed in theaforementioned application Ser. No. 392,404, (now abandoned,) in thenames of Miller, et al. and in U.S. Pat. No. 3,455,721, issued July 15,1969 in the names of Phillips, et al. and issued as U.S. Pat. No.3,455,721 on July 15, 1964 can be employed in compositions useful forcoating mark-forming materials into supporting sheets. An example of thecompositions which can be coated onto the receiving surface of anunderlying sheet of a multi-sheet to react with a cap sule coating onthe underside of an overlying sheet is as follows:

materials of this invention and preferred methods for utilizing thechromogenic materials, in combination with other materials, as reactivecomponents in markforming record material; examples will now bedisclosed wherein preparation of several of the chromogenic materials isdescribed.

EXAMPLE 1 Preparation of 2-formyl-6'-diethylaminofluoran A reactionmixture of 3.1 grams of 2-carboxy-4-diethyl-amino-2'-hydroxybenzophenone, 1.2 grams ofp-hydroxybenzaldehyde, and 20 milliliters of 90 percent, by weight,aqueous sulfuric acid solution was heated for about 1 hour at l40-145 C.The reaction mixture was then poured into about 250 milliliters of waterand made alkaline to a pH of above about 8 by addition of dilute,aqueous, ammonium hydroxide solution. The reaction mixture was extractedby 250 milliliters of benzene and the benzene extract was washed withsodium hydroxide solution and then with water. The reaction product waschromatographically purified over alumina. A benzene solution of thepurified reaction product imparted an orange color to paper coated witha mixture of kaolin and phenolic resin.

EXAMPLEZ Preparation of 2-carbomethoxy-6- diethylaminofluoran A reactionmixture of 1.6 grams of 2-carboxy-4-diethylamino-Z'-hydroxybenzophenone, 0.76 grams ofmethyl-p-hydroxybenzoate and 20 milliliters of percent, by weight,aqueous sulfuric acid solution was heated for about 5 hours at 98-102 C.The reaction mixture was then poured into water and made alkaline to apH of above about 8 by addition of dilute, aqueous, ammonium hydroxide.The reaction mixture was extracted by benzene, washed and concentratedby evaporation. The crude product was chromatographically purified overalumina. A benzene solution of the purified product imparted an orangecolor to paper coated with a mixture ofkaolin and phenolic polymer.

EXAMPLE 3 Preparation of 2'-benzoyl-6'-diethylamino-4'- methylfluoran Areaction mixture of 0.3 grams of 2-carboxy-4'-diethylamino-2-hydroxybenzophenone, 0.2 grams of4'-hydroxy-3'methylbenzophenone, and 10 milliliters of 80 percent, byweight, aqueous sulfuric acid solution was heated fro about 1 hour at-l40 C. Reaction product isolation and purification was conducted asdescribed in the previous examples, above. A benzene solution of thepurified reaction product imparted an orange color to paper coated witha mixture of kaolin and phenolic resin.

What is claimed is:

1. A pressure sensitive record unit comprising:

a. support web or sheet material,

b. mark-forming components and a releasable liquid solvent for saidmark-forming components arranged in contiguous juxtaposition andsupported by said sheet material,

c. said mark-forming components comprising at least one chromogenicmaterial of the structure:

R, represents -CO-R.,, wherein R represents a chemical radical selectedfrom the group consisting of hydrogen, OCl-1 and R represents chemicalradicals selected from the group consisting of hydrogen and alkylradicals having less than five carbon atoms; and

R represents a chemical radical selected from the group consisting ofhydrogen and alkyl radicals having less than five carbon atoms;

2. The record unit of claim 1 wherein at least one of the mark-formingcomponents is maintained in isolation from the other mark-formingcomponents prior to the release of the solvent.

3. The record unit of claim 1 wherein the liquid solvent is present asthe nucleus of a microcapsule.

4. The record unit of claim 1 wherein the chromogenic material isdissolved in the liquid solvent prior to pressure release.

5. The record unit of claim 1 wherein the mark-formin g components andthe liquid solvent are present in a single support sheet.

6. The record unit of claim 1 wherein at least one member selected fromthe group consisting of the mark-forming components and the liquidsolvent is present in a support sheet other than the support sheethaving the remaining members of the group.

7. The record unit of claim 1 where the electron-accepting material ofthe Lewis acid type comprises a clay.

8. The record unit of claim 1 where the electron accepting material ofthe Lewis acid type comprises at least one organic polymer.

9. The record unit of claim 8 where the organic polymer is a phenolicpolymer.

10. The recordunit of claim 1 wherein the chromogenic material includesthe compound 6- diethylamino-2-formylfluoran.

11. The record unit of claim 1 wherein the chromogenic material includesthe compound 2'-carbomethoxy-6'-diethylaminofluoran.

12. The record unit of claim 1 wherein the chromogenic material includesthe compound 2'- benzoyl-6'-diethylamino-4-methyl-fluoran.

13. A mark-forming unit, comprising: a first web or sheet having on onesurface a transfer coating which contains as a finely dispersed phase aplurality of minute, pressure-rupturable capsules containing as an innerphase a solvent vehicle; a second web or sheet having an adherentcoating upon its surface or dispersed within said web or sheet, saidfirst and second webs or sheets being maintained disposed together infact-to-face relationship with said respective transfer and adherentcoatings in contiguity with each other; a first coating constituent inthe form of a substantially colorless or slightly colored chromogenicmaterial which includes as a major functional arrangement the molecularstructure wherein:

R, represents CO-R.,, wherein R represents a chemical radical selectedfrom the group consisting of hydrogen, OCH and R represents chemicalradicals selected from the group consisting of hydrogen and alkylradicals having less then five carbon atoms; and

R represents a chemical radical selected from the group consisting ofhydrogen and alkyl radicals having less than five carbon atoms;

and a second constituent in the form of an electronaccepting material ofthe Lewis acid type; one of said constituents being dissolved in saidsolvent liquid vehicle present as the inner phase of the plurality ofminute pressure-rupturable capsules in the transfer coating on or withinsaid first web or sheet, and the other of said coating constituentsbeing bonded to said second web in said adherent coating thereon butbeing accessible to other materials coming into contact with portions ofthe adherent coating, whereby, upon local impact and rupture of saidcapsules, releasing said liquid vehicle containing one coatingconstituent from at least some of the capsules onto said contiguousadherent coating, reactive contact is effected between said twoconstituents to produce a darkcolored material by the action of saidelectron-accepting material of the Lewis acid type upon said chromogenicmaterial to effect color change in said chromogenic compound to saiddark-colored material.

14. The mark-forming unit of claim 13 in which the electron-acceptingmaterial of the Lewis acid type comprises a clay.

15. The mark-forming unit of claim 13 in which the electron-acceptingmaterial of the Lewis acid type comprises an organic polymer.

16. The mark-forming unit of claim 15 in which the organic polymer is aphenolic polymer.

17. The record unit of claim 13 wherein the chromogenic materialincludes the compound 6- diethylamino-2-formylfluoran.

18. The record unit of claim 13 wherein the chromogenic materialincludes the compound 2'-carbomethoxy-6-diethylaminofluoran.

19. The record unit of claim 13 wherein the chromogenic materialincludes the compound 2'- benzoyl-6'-diethylamino-4'-methyl-fluoran.

1. A pressure sensitive record unit comprising: a. support web or sheetmaterial, b. mark-forming components and a releasable liquid solvent forsaid mark-forming components arranged in contiguous juxtaposition andsupported by said sheet material, c. said mark-forming componentscomprising at least one chromogenic material of the structure:
 2. Therecord unit of claim 1 wherein at least one of the mark-formingcomponents is maintained in isolation from the other mark-formingcomponents prior to the release of the solvent.
 3. The record unit ofclaim 1 wherein the liquid solvent is present as the nucleus of amicrocapsule.
 4. The record unit of claim 1 wherein the chromogenicmaterial is dissolved in the liquid solvent prior to pressure release.5. The record unit of claim 1 wherein the mark-forming components andthe liquid solvent are present in a single support sheet.
 6. The recordunit of claim 1 wherein at least one member selected from the groupconsisting of the mark-forming components and the liquid solvent ispresent in a support sheet other than the support sheet having theremaining members of the group.
 7. The record unit of claim 1 where theelectron-accepting material of the Lewis acid type comprises a clay. 8.The record unit of claim 1 where the electron accepting material of theLewis acid type comprises at least one organic polymer.
 9. The recordunit of claim 8 where the organic polymer is a phenolic polymer.
 10. Therecord unit of claim 1 wherein the chromogenic material includes thecompound 6''-diethylamino-2''-formylfluoran.
 11. The record unit ofclaim 1 wherein the chromogenic material includes the compound2''-carbomethoxy-6''-diethylaminofluoran.
 12. The record unit of claim 1wherein the chromogenic material includes the compound2''-benzoyl-6''-diethylamino-4''-methyl-fluoran.
 13. A mark-formingunit, comprising: a first web or sheet having on one surface a transfercoating which contains as a finely dispersed phase a plurality ofminute, pressure-rupturable capsules containing as an inner phase asolvent vehicle; a second web or sheet having an adherent coating uponits surface or dispersed within said web or sheet, said first and secondwebs or sheets being maintained disposed together in fact-to-facerelationship with said respective transfer and adherent coatings incontiguity with each other; a first coating constituent in the form of asubstantially colorless or slightly colored chromogenic material whichincludes as a major functional arrangement the molecular structure 14.The mark-forming unit of claim 13 in which the electron-acceptingmaterial of the Lewis acid type comprises a clay.
 15. The mark-formingunit of claim 13 in which the electron-accepting material of the Lewisacid type comprises an organic polymer.
 16. The mark-forming unit ofclaim 15 in which the organic polymer is a phenolic polymer.
 17. Therecord unit of claim 13 wherein the chromogenic material includes thecompound 6''-diethylamino-2''-formylfluoran.
 18. The record unit ofclaim 13 wherein the chromogenic material includes the compound2''-carbomethoxy-6''-diethylaminofluoran.